1. Field of the Invention
The present invention relates to a draining device for a rotating electric machine which is used for a starter, for instance, with the engine of an automobile.
2. Discussion of the Background
FIGS. 5a to 5d show a conventional draining device for a starter disclosed in, for instance, Japanese Unexamined Utility Model Publication No. 18653/1985. In FIG. 5, reference numeral 1 designates a rear bracket in a d.c. motor for a starter, numeral 2 designates a draining hole formed in the rear bracket 1, numerals 3a, 3b respectively designate bolt holders attached onto the outer circumferential wall of the rear bracket 1 at positions opposing to each other and for supporting bolts (not shown) Each of the bolt holders is prepared by punching and pressing a soft steel shaft, and they are firmly attached to the rear bracket by means of projection welding. Reference numerals 4 indicate the locations where projection welding is carried out. The holder 3b has an extension which forms a supporting piece 5 having a U-shape in cross section which covers the draining hole 2 in bridge form.
In the draining device constructed as above-mentioned, water is discharged through the draining hole 2 in the rear bracket 1 even though it enters the d.c. motor. On the other hand, invasion of dust or muddy water into the rear bracket 1 through the draining hole 2 is blocked because the draining hole 2 is covered by the supporting piece 5 in the bridge form.
In the conventional starter, although water splashed from the direction just below the rear bracket 1 is blocked by the supporting piece 5 and the water does not enter into the bracket 1 through the draining hole 2, there is a possibility that water enters into the rear bracket 1 through the draining hole 2 when the water is splashed upwardly at an angle with respect to the vertical center line of the d.c. motor, as indicated by arrow marks in FIG. 5d. Thus, the brushes and brush holders become rusty due to the water staying in the rear bracket 1, whereby there is caused a faulty sliding movement between the brushes and commutator.